Crane Wire Rope

7/30/2019 Crane Wire Rope

1/32

1

CRANE WIRE ROPE

Maintenance, Inspection and Rejection Criteria


2/32

2

Recommended Maintenance, Inspection and Rejection Criteria for Crane Wire

Ropes

1. PURPOSE - GUIDE FOR INSPECTING CRANE WIRE

The purpose of inspecting a crane wire rope is to supervise the normal process of

deterioration so that rope can be removed from service before becoming a hazard

to safety. Every wire rope will fail if it is not taken out of service at theappropriate time. If we select the right wire rope, we must understand the design

and operation factors that influence the life of wire rope, where and how to detect

changes in wire rope conditions, how to maximize rope life cycle and avoid a

reoccurrence of same failures (provide safe and economic operation).

Some sections of wire rope will go through a greater number of bends over sheaves

and drums than the rest. The area that has higher number of cycles requires a

close examination.

Very few if any offshore crane ropes are discarded through pure bend fatigue andthe majority of ropes are discarded due to mechanical/drum damage, either as a

result of crushing or plucking of the wires at the spooling cross-over regions due to

abrasion. Corrosion is also a prime mode of rope deterioration offshore and to

extend rope service life demands good inspection, maintenance and rejection

criteria based on the approved standards.

It is essential to have and maintain a crane wire inspection program and be able to

assess wire rope and crane history. When crane wire is replaced, it is as essentialas replacing old wire with new, to investigate why, what factors influenced wire

deterioration and determine if anything can be done to extend life of wire rope.This must be recorded and shared with rest of fleet as well as the crane and wire

manufacturer. (There is no benefit in replacing wire rope that will fail the same asthe previous one.)

Standard ropes


3/32

3

Inspection and rejection criteria are based on the ISO 4309 Code of practice for

the examination and discard of the crane wire rope. The discard criteria from ISO

4309 are explained also in this bulletin.

Specialty ropes

Internal inspection of specialty wire ropes may require NDT methods, to be

determined by the wire rope examiner. For external inspection standard methods

apply.

Applicable standards

ISO 4308-1 Cranes and Lifting Appliances Selection of Wire Ropes

ISO 4309 Cranes Wire ropes Code of practice for examination and discard

BS 6570 The Selection, Care and Maintenance of Steel Wire RopesEN 10264 2002 Steel Wire and Wire Products Steel wire for ropes

API 2D Recommended practice

2. DAILY

3. VISUAL DAILY INSPECTION BY OPERATOR

Visual inspection of critical points by operator:

Special attention should be given to sections of ropes that run over sheaves and

drums, including parts that are located next to the compensating assemblies andanchor points.

Plus sections of rope that become wet or that are exposed to heat and aggressive

environment (salt water, exhaust gases, dust from cement, barites and other

chemicals)

4. MONTHLY

Check the over-all condition of all of the wire ropes, including the end terminations.

Inspect the reeving. configurations of the wire ropes of the crane, to see ifthey comply with the manufacturers recommendations.

(Wherever possible the reeving should be symmetrical, this is for reasons of

safety, plus for getting the optimum longevity of service life from both

sheaves and wire rope together).

* Non-Symmetrical Reeving, especially the Laced-Block type is a poor excuse

for crane rigging and reeving practices. It should be avoided, as it contributes

to premature sheave and wire rope wear, as well as being a contributing factor

to the adverse side loading of certain types of crane booms under certain

operating circumstances.


4/32

4

Complete filling in the crane wire rope examination/discard record report.

Using a Vernier Caliper Gauge, measure rope diameter (always-select the part ofthe rope that travels the most through sheaves each crane will be specific

according to the operational conditions and reeving).

Check all rope terminations for damage, wear, fatigue, corrosion, broken wires, and

the terminations arrangement components and fasteners(i.e: bolts, nuts, wedges

and clamps) If required lubricate wire rope using pressure lubricator.

5. ANNUAL

The person having completed a recognized wire rope examiners course shall

perform the annual inspection and complete the crane wire examination/discardrecord.

If the condition of wire rope is acceptable in accordance with ISO 4309 and thereare no broken wires, the rope can safely continue to be used up to a maximum

service life of three years.

In some instances NDT methods might be needed to safely extend useful life ofthe rope. The wire rope inspector shall determine if NDT is required. If NDT is

used to extend/reject life of the rope a copy of the NDT record has to be includedin the inspection/rejection report.

If there is indication of wire rope deterioration necessitating discard of the saidwire rope it shall be in accordance with the criteria as described in section 3.5 of

the Code of Practice ISO 4309.

However, as a new simplified user-friendly version of ISO 4309 is due out in the

near future,

SPDC then with the present ISO 4309, would recommend (after discussion with

Bridon Ropes) using the following nine points of consideration when inspecting wire

ropes. These nine points are more in line with the contents of the new COP than the

current one, hence our recommendation to use them for wire rope inspection. Theyare all, of course, based on ISO 4309. They are as follows:

1. Randomly distributed broken wires.

2. Wear both internal & external and for abrasion.

3. Localized groups of broken wires.

4. Broken wires at the termination.

5. Deterioration of the rope core.

6. Thermal damage.

7. Corrosion - Internal.


5/32

5

8. Corrosion external.

9. Rope deformations.

The above 9 points can then be split in to three categories; for the first category 1

& 2, the inspector needs to count the randomly distributed broken wires and if the

discard figure is reached, the rope rejected or otherwise left in service. For the

second category 3, 4, 5, 6 & 7, it is a simple situation of if it is seen the rope should

be rejected, if not the rope remains in service. For the third category 8 & 9, if

these are seen, the inspector needs to make a judgment as to how severe it is and

should the rope remain in service.

We can now consider the individual points, knowing the crane ropes selected

incorporate plastic to primarily, increase bend fatigue life, reduce reduction in

diameter and prevent internal contamination.

1. Randomly distributed broken wires -

For the main and auxiliary hoists (Dyform 34LR-PI), if 2 or more visible brokenwires are found over a rope length of 6d or if 4 or more visible broken wires are

found over a rope length of 30d, the rope should be discarded.

For the boom hoists (Dyform 8x19-PI), if 5 or more visible broken wires are foundover a rope length of 6d or if 10 or more visible broken wires are found over a rope

length of30d, the rope should be discarded.

For the boom hoists (Dyform 8x26-PI), if 9 or more visible broken wires are

found over a rope length of 6d or if 18 or more visible broken wires are found over

a rope length of

30d, the rope should be discarded.

For the boom hoists (Dyform 8x36-PI), if 12 or more visible broken wires are

found over a rope length of 6d or if 24 or more visible broken wires are found overa rope length of 30d, the rope should be discarded.

Randomly visible broken wires are assumed to be the result of bend fatigue and

therefore should be evenly distributed over the length of rope experiencing the

most bending over sheaves.

2. Wear both internal & external and for abrasion - if the rope diameter is reduced

by (3% for main & auxiliary) (7% for boom) or more from the nominal rope

diameter, the rope should be discarded. Any reduction in the rope diameter


6/32


7/32

7

8. Corrosion external - if external corrosion is found, it is normally the judgment of

the inspector to determine the level of severity and to decide if the rope should

remain in service or not.

9. Rope deformations - if rope deformations are found, it is normally the judgment

of the inspector to determine the level of severity and to decide if the rope should

remain in service or not.

The most important thing is to record and detail clearly the results of the

examination and to produce a record that allows the cumulative effect of points 1,

2, 8 and 9 above to be taken in to account. Furthermore, we advise using the

preceding nine points of wire rope inspection at least until the new edition of ISO

4309 is in use. However, the present Section 3.5 of ISO 4309 is as follows:

3.5.1 Nature and Number of Broken Wires

In the case of 6- and 8-strand ropes, broken wires occur principally at the external

surface. This does not apply to wire ropes having a number of layers of strands(Typically multi-strand constructions), where the majority of breaks occur

internally and are therefore non-visible fractures

Tables 1 and 2 take these factors into consideration when considered in conjunctionwith the factors given in 3.5.2 to 3.5.11

When establishing rejection criteria for rotation-resistant ropes, consideration

shall be given to the rope construction, length of service and the way in which the

rope is being used. Guidance to the number of visible broken wires which shall give

rise to rejection is given in table 2.

Particular attention shall be paid to any localized area which exhibits a dryness or

denaturing of the lubrication.

Table 1 - Guidance for the number of broken wires in round strand ropes

working in steel sheaves


8/32

8


9/32

9

Table 2 - Guidance for the number of broken wires in rotation-resistant ropes

working in steel sheaves

3.5.2 Broken Wires at Termination

Broken wires at, or adjacent to, the termination, even if few in number, are

indicativeof high stresses at this position and may be caused by incorrect fitting of the

termination. Investigation of the cause of this deterioration shall be made, and,

where possible, the termination should be remade, shortening the rope if sufficient

length remains for further use. The termination should be done only by qualified

personnel.

3.5.3 Localized grouping of broken wires

Where broken wires are very close together, constituting local grouping of such

breaks, the rope shall be discarded. If the grouping of such breaks occurs in alength less than 6d or is concentrated in any one strand, it will be prudent to

discard the rope even if the number of wire breaks is smaller than the maximum

number indicated in tables 1 and 2.

3.5.4 Rate of increase of broken wires

In applications where the predominant cause of rope deterioration is fatigue, thecommencement of broken wires will begin after a certain period of usage, but the

number of breaks will progressively increase at ever-shortening intervals.


10/32

10

In these cases, it is recommended that careful examination and recording of the

increase of broken wires should be undertaken with a view to establishing the rate

of increase of the breaks. An application of this law may be used in deciding thefuture date for rope discard.

3.5.5 Fracture of strands

Small deterioration may not be so apparent from normal examination, particularly if

the rope stresses are well balanced throughout the individual strands. However, the

condition may result in a high loss of rope strength, so that any suggestion of suchinternal deterioration shall be verified by internal examination procedures. Where

such deterioration is confirmed, the wire rope shall be discarded (see annex D)

3.5.6 Reduction of rope diameter resulting from core deterioration

Reduction of rope diameter resulting from deterioration of the core can be causedby

a) Internal wear and indentation;

b) Internal wear caused by friction between individual strands and wires in therope, particularly when it is subject to bending;

c) Deterioration of a fibre core;

d) Fracture of a steel core;

e) Fracture of internal layers in a multi-strand construction.

If these factors cause the rope diameter (average of two diameter measurements

normal to each other) to decrease by 3 % of the nominal rope diameter for rotation

resistant ropes, or 10 % for other ropes, the ropes shall be discarded even if no

broken wires are visible.

3.5.7 External wear

Abrasion of the crown wires of outer strands in the rope results from rubbing

contact, under pressure, with the grooves in the pulleys and the drums. The

condition is particularly evident on moving ropes at points of pulley contact when

the load is being accelerated or decelerated, and shows itself as flat surfaces onthe outer wires.


11/32

11

Wear is promoted by lack of lubrication, or incorrect lubrication, and also by the

presence of dust and grit.

Wear reduces the strength of ropes by reducing the cross-sectional area of the

steel.

When owing to external wear the actual rope diameter has decreased by 7 % or

more of the nominal rope diameter, the rope shall be discarded even if no wire

breaks are visible.

3.5.8 Decreased elasticity

Under certain circumstances usually associated with the working environment, a

rope may sustain a substantial decrease in elasticity and will be unsafe for furtheruse. If a complete strand fracture occurs, the rope shall be discarded.

Decreased elasticity is difficult to detect: if the examiner is in any doubt, adviceshould be obtained from a specialist in ropes. However, it is usually associated with

the following:

a) Reduction of rope diameter;b) Elongation of the rope lay length;

c) Lack of gap between individual wires and between strands, caused by thecompression of the component parts against each other;

d) The appearance of fine, brown powder within the strand gussets;e) While no wire breaks may be visible, the wire rope will be noticeably stiffer to

handle and will certainly have a reduction in diameter greater than related purely to

wear of individual wires. This condition can lead to abrupt failure under dynamic

loading and is sufficient justification for immediate discard.

3.5.9 External and internal corrosion

Corrosion occurs particularly in marine and industrial polluted atmospheres, and will

not only diminish the breaking strength by reducing the metallic area of the rope

but will also accelerate fatigue by causing the irregular surface from which stresscracking will commence. Severe corrosion may cause decreased elasticity of the

rope.

a) External corrosion Corrosion of the outer wires may be detected visually.

b) Internal corrosion (see annex E, plate 7)

This condition is more difficult to detect than the external corrosion which

frequently accompanies it, but the following indications may be recognized:


12/32

12

1) Variation in rope diameter. In positions where the rope bends around pulleys, a

reduction in diameter usually occurs. However, in stationary ropes it is not

uncommon for an increase in diameter to occur due to the build-up of rust underthe outer layer of strands;

2) Loss of gap between the strands in the outer layer of the rope frequently

combined with wire breaks in the strand gussets. If there is any suggestion of

internal corrosion, the rope should be subjected to internal examination as

indicated in annex D; this shall be carried out by a competent person.

Confirmation of severe internal corrosion is justification for immediate rope

discard.

3.5.10 Deformation

Visible distortion of the rope from its normal formation is termed deformation

and may create a change at the deformation position which will result in an unevenstress distribution in the rope.

Distinction is made between the following main deformations of rope on the basis

of their appearance (see 3.5.10.1 to 3.5.10.9):

a) Wavinessb) Basket or lantern distortion

c) Strand extrusion

d) Wire extrusion

e) Local increase in the diameter of the rope

f) Local decrease in the diameter of the rope

g) Flattened portions

h) Kinks or tightened loops

i) Bends

3.5.10.1 Waviness (see annex E, plate 8)

Waviness is a deformation where the longitudinal axis of the wire rope takes the

shape of a helix. While not necessarily resulting in any loss of strength, such a

deformation, if severe, may transmit a pulsation resulting in irregular rope drive.

After prolonged working, this will give rise to wear and wire breaks.

In the case of waviness (see figure 1), the wire rope shall be discarded if:


13/32

13

d1 > 4d/ 3

Where dis the nominal diameter of the rope and d1, is the diameter correspondingto the envelope of the deformed rope, and the length of the rope underconsideration does not exceed 25d.

Figure 1 waviness.

3.5.10.2 Basket or lantern distortion (see annex E, plate 9)

This condition occurs in ropes having a steel centre (or core) when the outer layer

of strands has become dislocated, or when the outer layer becomes longer than the

inner layer of strands. Such a condition may occur as a result of abrupt (snatch)loading of the rope from a slack condition.

A basket or lantern formation is justification for immediate discard.

3.5.10.3 Strand extrusion (see annex E, plate 10)

This feature is frequently associated with basket or lantern deformation where the

rope imbalance is indicated in the extrusion of the core.Strand extrusion is justification for immediate discard.

3.5.10.4 Wire extrusion (see annex E, plates 11 and 12)

In this condition, certain wires or groups of wires rise up, on the opposite side of

the rope to the pulley groove, in the form of loops - this feature usually results

from shock loading.

If the deformation is severe, there is justification for rope discard.3.5.10.5 Local increase in diameter of rope

(see annex E, plates 13 and 14)


14/32

14

A local increase in rope diameter may occur and could affect a relatively long length

of the rope. The condition usually relates to a distortion of the core (in particularenvironments, a fibre core can swell up owing to the effect of moisture) and

consequently it creates imbalance in the outer strands, which become incorrectly

oriented.

A severe condition is justification for rope discard.

3.5.10.6 Local decrease in diameter of rope (see annex E, plate 17)

A local decrease in the diameter of the rope is frequently associated with fracture

of a core. Positions close to terminations shall be carefully examined for suchdeformations.

A severe condition is justification for rope discard.

3.5.10.7 Flattened portions (see annex E, plates 18 and 19)

Flattened portions occur as a result of mechanical damage; if severe, they arejustification for rope discard.

3.5.10.8 Kinks or tightened loops (see annex E, plates 15 and 16)

A kink or tightened loop is a deformation created by a loop in the rope which hasbeen tightened without allowing for rotation about its axis. Imbalance of lay length

occurs, which will cause excessive wear, and in severe cases the rope will be so

distorted that it will have only a small proportion of its strength remaining.

A kink or tightened loop is justification for immediate discard.

3.5.10.9 Bends (see annex E, plate 20)

Bends are angular deformations of the rope caused by external influence.

The condition is justification for immediate discard.

3.5.11 Damage due to heat or electric arcing

Wire ropes which have been subjected to exceptional thermal effects, externally

recognized by the colours produced, shall be discarded.


15/32

15


16/32

16


17/32

17


18/32

18


19/32

19


20/32

20


21/32

21


22/32

22


23/32

23


24/32

24


25/32

25


26/32

26


27/32

27


28/32

28

Whilst inspecting the wire ropes, all the other reeving components in the system,

shall be examined, including sheaves, drums, rollers, end terminations or any other

part that is directly or indirectly associated with wire rope arrangement.

Note:

Installation procedure of new wire rope is to be followed as per crane wire rope and

crane manufacturer recommendations. However, when installing Metric crane wire

ropes onto the older American made Cranes, that usually have the wider, but

smaller diameter, smooth (no grooved) drums, which were originally designed for

use with API Spec/Imperial measurement ropes. The following recommendationsshould be adhered to:

Care and diligence must be exercised when winding the rope onto the drum at the

correct tension.

Which is a minimum tension of 10% of SWL, based on a 5:1 design factor.

Or, in other words, 2% of the MBL of the rope.

The reason for the precautionary request for diligence is two-fold: (1) for safetyand (2) because of the potential problems that any incompatibility between metric

rope and imperial sized drum.

The best tool to use to hold the correct tension on the line being wound onto the

drum, is a pinch-roller type line tensioner in conjunction with a Martin Decker

Load Cell.

As the bottom layer of wraps are wound upon the drum under tension, they should

be carefully blocked hard against each other and up against the flange of the

drum the first wrap is anchored to. (To avoid cable damage, this should be done

preferably with a soft Mallet, or if not, a wooden 2x4 and a hammer)

As the wraps being would onto the drum, fill the bottom layer of the drum, any

gap between the last wrap of the layer and the other drum flange should be filled in

with soft line tapped in hard carefully with a hammer or Mallet and taped in

position with duct tape, for safety.

The other layers on the drum, above bottom layer will spool correctly now, butshould still be put on at the minimum recommended tension.


29/32

29

During new wire rope installation total length of wire rope is to be lubricated using

pressure lubricator.

A recognized inspector can be 3rdparty or rig personnel that have completed arecognized wire rope examiners training course.

CRANE WIRE ROPE INSPECTION/DISCARD LOG

(to be completed monthly/annually)

DESIGN FACTORS INFLUENCING FATIGUE LIFE OF THE WIRE ROPE

Design factor

Are controlled by the crane manufacturer, with factors like sheave specification,Diameter of Tread to diameter of rope ratio, type of bearings, sheaves groove

radii and throat angles versus fleet angles of hoist lines, contact angles, tensilestrength, bends and others

Operating factors

Are: The installation and breaking-in of the rope, the safety factor it is operatedat load wise,

Inadvertent shock-loading, lubrication, inspection and maintenance

OPERATING FACTORS INFLUENCING FATIGUE LIFE OF THE WIRE ROPE

Storage

Wire ropes shall be stored in the warehouse, or an equivalent protected controlled

environment.

They have to be protected from all of the elements of nature: sun, rain, sleet,

snow, humidity and exposure to a marine environment.

Reels of any wire rope that has been heavily lubricated at each stage of itsmanufacture

(Winding, stranding & closing) do need to be turned on a regular basis to prevent

migration of the lubricant.

Installation

Prior to installing any new wire rope, inspect sheaves and drums. Ensure that thedrums and sheaves are in the good conditions (there are no advantages to install

new rope in worn or damaged sheaves and drum grooves). If any wire rope has to be

discarded prematurely, or for any reason other than fair wear and tear, then the


30/32

30

cause of the ropes demise needs to be investigated, resolved, explained and

documented.

While installing new rope ensure that complete length of the rope is lubricatedusing Masto pressure lubricator. This will ensure that any moisture is removed and

total length of rope is properly lubricated. If pressure lubrication is not applied,

moisture can become corrosion which can greatly reduce life of the wire rope.

Wire rope should be installed under as much load as possible. The amount of load

recommended is approximately 5-10% of minimum breaking load. Insufficient

tension on the bottom wraps can create a multitude of problems. The absolute

minimum of tension that a wire rope should be wound onto a drum at, is 10% of

SWL, based on a design factor of 5. Which equates to 2% of minimum breaking

load.

Also on smooth drums, especially those, that for the majority of their operatingtime are in a single layer operating mode, the correct lay of rope for the type of

wind and the direction of spooling is very important.

And should be as follows:

a) Over-wind left to right, use right lay rope.

b) Under-wind right to left, use right lay rope.


31/32

31

FIGURE 1 CORRECT METHOD FOR LOCATING THE ROPE ANCHORAGE

POINT ON A DRUM.

c) Over-wind right to left, use left lay rope.d) Under-wind left to right, use left lay rope.

(The above directions of spooling per rope lay, apply with the observer standing behind the drum

and looking towards the direction of rope travel).

The reason for this is: When a rope onto a drum, any tendency for the rope

to twist when tension is released, will be in a direction that would untwist the

rope at the free end.

So the advantage in applying the rope in proper direction of lay is that when

the load is slacked off, the several coils of rope on the drum will hug togetherand maintain a level and even layer.

However, with rope in improper direction of lay, each time that the load is

slacked off, the coils will spread apart and when the winding of the rope back

onto the drum resumes, it often results in the rope criss-crossing, overlapping

and drum-crushing or flattening the unevenly spread coils on the drum.

The reel of the new wire rope and the first sheave must rotate in the same

direction to avoid reverse bend reeving and installation of a twisted rope. (In other

words reeve the crane from the reel to first sheave correctly either over-wind to

over-wind, or under-wind to under-wind) as appropriate.When installing a new rope on a crane, the objective of the exercise is to

install/reeve the new rope without inducing any turn into it. Whether reeving the

new rope with the old rope that its replacing, or by using a messenger line (which

should be suitably torque-matched to the new rope).

Join the two together with a wire stringing grip (also known as a snake, sock,Chinese finger)

DO NOT USE A SWIVEL TO JOIN THE 2 HALVES OF THE SNAKE

TOGETHER DURING THE INSTALLATION OF THE ROPE.

The new rope should be marked or flagged so that during reeving, any turn can be

monitored

and taken out prior to the rope being anchored to the drum.

Breaking in

It is advisable when starting to use a new rope to let it set itself to the working

conditions by running it without a load and then for short period with light load.


32/32

32

Operation

Avoid kinks, shock-loading, over and cross winding.

Re-lubrication

When installing new rope and as required use Masto pressure lubricator.

Slip and cut

If capacity of drum allows extra wire consider slip and cut.

Date post:	14-Apr-2018
Category:	Documents
Upload:	rajmohan-babu
View:	227 times
Download:	0 times

Crane Wire Rope

Documents